Joe Pompei has taken ultrasound waveforms and converted them so that they are audible. What can you do with this? Well you now have the chance to whisper in someone’s ear from across the room.
Here’s a another great TED talk from Woody Norris on similar technology.
There’s a ton of information on this technology online. If you still interested in seeing more a simple Google search for “audio spotlight” will give you loads of information.